SCMOS rules, MOSFET width

Kenneth Joseph Hass <[email protected]> Thu, 30 Oct 2008 08:32:48 -0700 (PDT)
Newsgroups gmane.comp.cad.electric.bugs
Message-ID <[email protected]>
Dear Electric buglist,

I'm having a problem with MOSFETs when using the "Analog" technology option (actually it seems to be the choice of SCMOS rules rather than Submicron rules in the ProjectSettings->Technology menu).  Electric thinks the width of some transistors is 2 lambda bigger than it really is.

If I instantiate the P-Transistor-Scalable or N-Transistor-Scalable I get a MOSFET with a width of 3 lambda and the active region under the poly is correctly drawn at 3 lambda.  However, if I use the plain P-Transistor and N-Transistor components and check the properties of the transistors the width will be reported as 5 lambda, even though the transistors are drawn with an actual width of 3 lambda.  The offending transistors are also drawn with a 3 lambda extension of the gate rather than 2 lambda.

Moving the cursor over these transistors shows that Electric thinks the pin in the channel is extended 1 lambda beyond the active at each end, only for the plain transistors.

Deselecting the "ProjectSettings->Technology->Analog" option and changing from "SCMOS rules" to "Submicron rules" appears to fix the problem.

I'm using Electric 8.07 on Red Hat Enterprise 4 linux with java version 1.6.0_07. Am I doing something wrong here, or overlooking something?

Thanks,
Joe